Currently, a user using Global System for Mobile Communications (GSM) can obtain a network service only after inserting a subscriber identity module (SIM) card into a mobile phone. With development of the industry of mobile communications, mobile communications products have become necessities in people's life. It gradually becomes a common phenomenon that a user possesses two or more modems. Emergence of dual-SIM dual-standby mobile phones meets user's requirements, and a user can freely switch modems for communication according to requirements.
Two modems of a dual-SIM dual-standby mobile phone have respective paging cycles, and each modem receives, within a paging cycle of the modem, a signal sent by a base station to maintain a network connection. Usually, the mobile phone has two antennas for receiving signals. Performance of one antenna is good (the antenna can successfully receive a signal), and performance of the other antenna is poor (the antenna can hardly demodulate a signal). The prior art only enables each modem to use a fixed antenna but cannot ensure that each modem receives a signal by using a good antenna. For example, a good antenna is allocated to a primary modem, and a poor antenna is allocated to a secondary modem. In this way, the primary modem receives a signal by using a good antenna within a paging cycle of the primary modem, and performs normal communication. However, the secondary modem cannot receive a signal (or receives a very weak signal) by using a poor antenna within a paging cycle of the secondary modem, and consequently, the secondary modem is disconnected from a network.